EXTERNAL CHAEAOTEBS AND HABITS 101 He makes a rude and simple nest, which is only occupied at night. In captivity the young Gorilla usually manifests a sullen disposition, but that is not always the case, Occasionally it beats its chest, which resounds like a drum. Du Chaillu stated that the wild animal in the forests also thumped its chest till it resounded, but many disbelieved his statements. No adult animal has yet been captured alive and kept in captivity In any zoological gardens, and the number of young ones which have been on exhibition constitutes a verv small series. u Distribution.—The actual limits of the area of distribution are not yet known, but the region in which it lives is small compared with the area inhabited by the Chimpanzee. It is found in the moist, forest region on the banks of the Gaboon and other rivers in West Africa. Specimens have been obtained at Lake Kivu. Its distribution is becoming more restricted, for it was seen in large numbers on the coast about the middle of last century. Keith (99) enumerates the writers who have recorded localities in which it has been killed. Barnes has obtained Gorillas at the altitude of 6,000-10,000 feet in the Kivu District, Classification,—There appears to be only one species of Gorilla with several sub-species. Eothschild (485) recognizes the following varieties, which are distinguished by certain external and cranial characters :— (1) Gaboon Gorilla (Gorilla gorilla gorilla Savage and Wyman) :—Pelage dimorphic. Red phase does not differ on the body, but the whole crown becomes rufous. Occipital region narrow and triangular because the lamb-doid crest has a sharp centre.